1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to searching for erroneous data, and, more particularly, to searching for an erroneous data region of received data using a specified region prescribed in the data and compensating for the erroneous data region.
2. Description of the Related Art
With the spread of wireless networks, the transmission of mass multimedia data in wireless networks has been increasing, and effective data transmission methods for wireless network environments are required. In addition, wireless transmission of high-quality images, such as a digital video disk (DVD) images, high definition television (HDTV) images, and the like, among various home devices, is in demand.
At present, an IEEE 802.15.3c task group is considering a technical standard for transmitting large volumes of data in a wireless home network. This standard, known as Millimeter Wave (mmWave), uses an electromagnetic wave having a physical wavelength of several millimeters for transmission of the large volumes of data (that is, an electromagnetic wave having a frequency in the range of 30 GHz to 300 GHz). In the related art, this frequency band is an unlicensed band and is limitedly used for communication carriers, radio astronomy, or vehicle anti-collision.
FIG. 1 is a view explaining comparison of frequency bands between the IEEE 802.11 series standard and mmWave. In the IEEE 802.11b standard and the IEEE 802.11g standard, the carrier frequency is 2.4 GHz, and a channel bandwidth is about 20 MHz. Also, in the IEEE 802.11a standard and the IEEE 802.11n standard, the carrier frequency is 5 GHz, and a channel bandwidth is about 20 MHz. In contrast, in mmWave, a carrier frequency of 60 GHz is used, and the channel bandwidth is in the range of about 0.5 to 2.5 GHz. Accordingly, it can be seen that mmWave uses a much larger carrier frequency and channel bandwidth than the existing IEEE 802.11 series standards. As such, if a high-frequency signal having a wavelength in millimeters (mmWave) is used, a very high transmission rate of several Gbps can be obtained, and the size of an antenna can be set to be not more than 1.5 mm. Then, a single chip including the antenna can be implemented.
Recently, the transmission of uncompressed audio and/or video (AV) data (hereinafter referred to as “uncompressed AV data”) between wireless devices using a high bandwidth of the millimeter wave has been studied. Compressed AV data is lossy-compressed through processes, such as motion compensation Discrete Cosine Transform, (DCT) transform, quantization, variable length coding, and the like, such that portions that are less sensitive to the sense of sight or the sense of hearing of a human being are eliminated. In contrast, uncompressed AV data includes digital values representing pixel components (e.g., red (R), green (G), and blue (B) color components) as they are.
Accordingly, bits included in the compressed AV data do not have significance levels, while bits included in the uncompressed AV data have significance levels. For example, as illustrated in FIG. 2, in the case of an eight-bit image, one pixel component is composed of eight bit levels. Among them, the bit representing the highest degree (i.e., the bit of the highest level) is called a most significant bit (MSB), and the bit representing the lowest degree (i.e., the bit of the lowest level) is called a least significant bit (LSB). That is, the respective bits of one byte (i.e., eight bits) have different significance levels when restoring an image signal or an audio signal.
During the transmission of AV data, an error occurring in an upper significant bit can be detected more easily than that occurring in a lower significant bit. Accordingly, during a wireless data transmission, there is a greater necessity for preventing the occurrence of error in the upper significant bit data in comparison to the lower significant bit data.
Also, according to a method of detecting an error of data being transmitted, the erroneous data is searched for using the sum of checked values of the entire data set, and it is impossible to confirm the error has occurred in the MSB.
Accordingly, there is a need for a technique of detecting an error of the MSB of the transmitted data and receiving a retransmission of the MSB, and for a technique of compensating for erroneous data using the already transmitted data in the case where the retransmission of the MSB is difficult.